We consider a MIMO orthogonal frequency division multiplexing (OFDM) full-duplex ISAC system, and focus on the receiver design of the BS to jointly locating the positions of the devices and retrieving the information passively transferred by the RISs. OFDM technique, which transmits data symbols over orthogonal subcarriers, is popular for implementing ISAC systems. The authors of [1]} allocated different subcarriers to the communication and sensing functions, but this reduces the available bandwidth of each function. In [2]}, a high-resolution compressed sensing (CS) algorithm is proposed to solve the problem of joint delay-Doppler estimation of moving targets under the assumption that the signal is sparse in the Fourier-domain, but the computational cost is high while solving the problem of semidefinite program. The authors of [3]} derived a low-complexity subspace-based algorithm by applying a smoothing approach for joint estimation of range and Doppler shift in OFDM-based radar system, but the estimation accuracy for multiple targets is not high enough.
